In I think Gold/Silver(memory is fuzzy) they introduced Pichu(the 2nd one) as Pikachu's pre-evolution. The only way I can remember to get one was breeding pokemanz(some combination of a female Pikachu with something it's compatible with) and hatching the egg. Annoying pokemon if you ask me and was a pain to evolve since it required the whole friendship thing...plus it kinda sucked on Super smash bros. melee.